Camming mechanism



June 20, 1961 E. w. SWANSON CAMMING MECHANISM 2 Sheets-Sheet 1 Filed June 50, 1959 unli la,

INVENTOR. EDWARD 0! mm M June 20, 1961 E. w. SWANSON CAMMING MECHANISM 2 Sheets-Sheet 2 Filed June 30, 1959 INVENTOR. BY EDWAWN United States Patent 2,988,932 CAMMING MECHANISM Edward W. Swanson, Chicago, 11]., assignor to Admiral Corporation, Chicago, 111., a corporation of Delaware Filed June 30, 1959, Ser. No. 823,926

4 Claims. (Cl. 74-568) The present invention relates to a camming mechanism and, more particularly, to a cam and cam follower arrangement adapted to be used in an electrical circuit means.

It is an object of the present invention to provide a new and improved camming mechanism.

It is another object of the present invention to provide in a camming mechanism a new and improved cam button.

It is a further object of the present invention to pro vide a camming mechanism wherein a plurality of cam buttons are resiliently held and restrained against axial movement by a suitable support-yet can be rotated between operative and inoperative positions.

It is yet another object of the present invention to provide in a camming mechanism a support which maintains a plurality of camming buttons in predetermined position during and after adjustment of the buttons between their operative and inoperative positions.

It is a further object of the present invention to provide in a camming mechanism a new and improved cam button embodying an adjusting head, a camming part, and a supporting portion located intermediate the adjusting head and camming part.

It is yet a further object of the present invention to provide a camming arrangement that can be used with a conventional spur gear, thereby obviating the need for a rotatably mounted support.

The above and other objects are realized in accordance with the present invention by providing a new and improved cam and cam follower arrangement adapted to control an electrical circuit means. The cam and cam follower arrangement embodies a movable support provided with a plurality of apertures for respectively accommodating a plurality of cam buttons, the buttons coacting with a cam follower that controls a pair of contacts. The contacts are electrically connected to the energizing circuit of a prime mover drivingly connected to the movable support. In one aspect of the invention, each cam button is so constructed that incident to its insertion through the aperture it is held in place and rest-rained against axial movement by its inherent resiliency. In another aspect of the invention, the camming button includes an adjusting head located adjacent to a support portion for coacting with the apertured support. The support portion is located intermediate the adjusting head and a camming part so that, incident to turning of the cam button, the adjusting head seats against the support to maintain the camming part in preselective position relative to the cam follower, irrespective of movement of the cam button.

The invention, both as to its organization and methd of operation, taken with further objects and advantages thereof, will best be understood by reference to the following description taken in connection with the accompanying drawings, in which:

FIG. 1 is a perspective view of a camming mechanism embodying the principles of the present invention;

FIG. 2 is an enlarged elevational view of a part of the camming mechanism of FIG. 1;

FIG. 3 is a sectional view taken along line 3-3 of FIG. 2;

FIG. 4 is a fragmentary elevational view, similar to FIG. 3, shown partially in section;

FIG. 5 is a greatly enlarged view of a cam button and a cam follower embodied in the mechanism of FIG.

2 1, illustrating the cam button in its inoperative position out of engagement with the cam follower;

FIG. 6 is a view similar to FIG. 5, illustrating the' cam button in its operative position in engagement with the cam follower; and

FIG. 7 is a perspective view of another embodiment of the camming mechanism of FIG. 1.

Referring now to the drawings, a first embodiment of a camming mechanism embodying the features of the present invention is illustrated in FIGS. 1 through 6, while a second embodiment of a camming mechanism embodying the features of the present invention is illustrated in FIG. 7. Each of the embodiments of the camming mechanism is adapted to be used with an electrical circuit means (not shown) which controls the movement of a control shaft. Briefly, the camming mechanism is drivingly connected to the control shaft and is adapted to be preset so that in certain predetermined positions of the camming mechanism the circuit means operates to stop the control shaft in correspond ing positions. Although the camming mechanism is described as being a programming device used to control the movement of a main tuning shaft of a television receiver, it should not be construed as being limited or restricted to this use since the invention has a wide variety of applications in other fields. the camming mechanism of the present invention has proven to be extremely more accurate in its control function and is more rugged and sturdy than existing camming mechanisms.

Considering now the FIG. 1 embodiment, a camming mechanism embodying the features of the present invention is illustrated and is referred to generally by reference numeral 10. The camming mechanism 10 controls the movement of a control shaft 12 by controlling the energizing circuit (not shown) of a suitable prime mover, for example an electric motor (not shown) that is drivingly connected to the control shaft 12 by a suitable gearing mechanism. The control shaft 12 in certain applications actually comprises the main tuning shaft of a television receiver and in other applications the control shaft 12 is drivingly connected to the main tuning shaft of the receiver to assume corresponding angular positions to the main tuning shaft. In any event, for the purpose of this description, the control shaft 12 will be considered as the main tuning shaft of the receiver and will be so identified hereafter. Briefly, the camming mechanism 10 comprises a plurality of cam buttons 14 spatially supported on a disc and hub arrangement 20, 21 which, in turn, is fixedly secured to the main tuning shaft 12. The cam buttons 14 are representative of discrete angular positions corresponding to channel positions of the main tuning shaft 12. Accordingly, since only selected ones "of the channels in particular areas are transmitting channels, selected ones of the cam buttons 14 corresponding to the transmitting channels are turned by an adjusting device 13 to their operative positions while the balance of the cam buttons 14 are turned to their inoperative positions. Each cam button 14 when in its operative position coacts with a cam follower 16 to open a pair of contacts 18 electrically connected in a holding circuit (not shown) for the electric motor (not shown), thereby to deenergize the motor and to stop the main tuning shaft 12. The holding circuit is connected in parallel with an energizing circuit including a pair of control contacts that are either manually or remotely closed to energize the electric motor when it is desired to tune the receiver to another channel and, thus, move the main tuning shaft 12 to another channel position. The control con tacts (not shown) remain closed long enough to permit the cam button 14 to move out of engagement with the cam follower 16, thereby to close the contacts 18 and In any event,

assassin complete the holding circuit for the motor. Thus, the motor (not shown) is energized under the exclusive control of the camming mechanism to turn the main tuning shaft 12 to an adjacent transmitting channel position. During this movement, the hub and disc arrangement 20, 21 also turns and the cam buttons 14 move past the cam follower 16. The shaft 12 continues to turn under the control of the motor as long as cam buttons in their inoperative positions pass by the cam follower 16, since the inoperative buttons do not engage the cam follower 16 and, hence, do not open the holding circuit for the motor. The motor remains energized to turn the shaft 12 until a cam button 14 in its operative position coacts with the cam follower 16 and opens the holding circuit for the motor, thereby to stop the main tuning shaft 12 in an adjacent transmitting channel position. Hence, by this arrangement, the main tuning shaft 12 does not stop in every channel position, but only stops in the transmitting channel positions under the control of the camming mechanism 10.

As only shown in IFIG. 1, the main tuning shaft 12 is journaled in a support plate 24 by suitable bearing assemblies (not shown) to be right-angularly related to the support plate 24. The bearing assemblies are so constructed that the control shaft 12 is free to rotate yet is restrained against axial movement. As clearly shown, the main tuning shaft 12 extends to the right of the plate 24 (as viewed in FIG. l) and exclusively supports the disc and hub arrangement 20, 21 and the cam buttons 14. Although not illustrated, the shaft 12 extends to the left of the plate and is mechanically connected to the other tuner components of the television receiver.

The cam buttons 14 are equally spaced from one another, as well as from the main tuning shaft 12, by the disc and hub arrangement 20, 21 mounted on the main tuning shaft 12. More specifically, the hub 21 has an axially extending bore 26 which is slightly oversized to accommodate the main tuning shaft 12, thereby to permit the hub 21 to move axially along the shaft 12 into a predetermined position spaced from the support plate 24 and the cam follower 16. The hub 21 is fixedly secured to the shaft 12 by a setscrew 28 located in a transversely extending opening 30 which is internally threaded to accommodate the setscrew 28 (see FIG. 4). As clearly illustrated in FIG. 4, the left end of the hub 21 is cut away to define a collar 32 of reduced diameter. The body of the collar 32 extends through an opening 34 defined in the disc while the extreme ends of the collar 32 are peened over onto the disc 20 to provide a tight fit between the hub 21 and the disc 29. Consequently, the disc 20 rotates with the control shaft 12 as a result of the peening connection between the hub 21 and the disc 20 and the setscrew 28 connection between the hub 21 and the shaft 12.

Inasmuch as twelve VHF channel positions exist, twelve cam buttons 14 are employed to provide twelve discrete angular positions for the main tuning shaft 12 that are controllable by the camming mechanism 10. The twelve cam buttons 14 extend through a plurality of openings 36 defined in the disc 20. The openings 36 are circular and are equally spaced from one another adjacent to the periphery of the disc 20. The openings 36 are made at the same time and with the same tool that stamps the disc out of suitable stock material, for example a punch die or the like. Irrespective of the size of the contact buttons 14, the openings 36 are punched to have such a diameter that the contact members are able to be inserted into the openings 36 with a minimum amount of effort. In any event, the circular openings 36 define generally cylindrical surfaces that extend entirely through the disc 20 and are right-angularly related to the opposite sides of the disc 20. By this construction, the cam buttons 14 are orientated perpendicularly to the disc 20 and remain right-angularly related to the disc 26 regardless of whether or not the 4 cam buttons 14 are in their operative or inoperative positions or are being moved between these positions.

For the purpose of limiting the movement of the cam buttons 14 between their operative and their inoperative positions, i.e., prevent movement past designated angular position, a plurality of offset lugs 38 are stamped out of the disc 20 adjacent, respectively, to the openings 36, as best shown in FIG. 3. The lugs 38 are cut out of portions of the disc 20 immediately inwardly of the openings 36 along radial lines projected through the openings 36. Accordingly, the lugs 38 occupy the same positions relative to the openings 36 and each lug 38 coacts with each cam button 14 in an identical manner, as described below, to provide an operative and inoperative position for each cam button 14. v V

In accordance with an aspect of the present invention, each of the cam buttons 14 is so constructed that it is readily insert-able into an opening 36 of the disc 20 and once located in an opening 36 it is held in position against subsequent axial movement by the resiliency derived from its novel construction. However, although each cam button 14 is restrained against axial movement, each is able to rotate between its operative and inoperative Positions.

Considering now the constructional details of the cam button 14, attention is specifically directed to FIG. 5 wherein a cam button 14 is illustrated in its inoperative position out of engagement with the cam follower 16 and to FIG. 6 wherein a cam button 14 is illustrated in its operative position to coact with and displace the cam follower 16. Each of the cam buttons 14 comprises a shank 42 adapted to be inserted through and coact with the cylindrical surface of the openings 36 and further comprises an enlarged head 40 for abutting the right side of the disc 20 (as viewed in FIG. 1) to properly orient the button 14 relative to disc 2-0. More specifically, the enlarged head 40 is located at the extreme right end of the cam button 14 (as viewed in FIGS. 1, 5 and 6) and is provided with an adjusting slot 46 to receive the adjusting tool 13. The head 40, hereinafter referred to as an adjusting head 40, is of generally cylindrical shape and includes adjacent its left end (as viewed in FIGS. 5 and 6) an arcuate groove 48 for receiving the lug 38. The groove 48 extends over an angle of approximately degrees and includes at its ends a pair of spaced apart stops 50 and 52 which specifically abut the ing 38 to limit the turning of the cam button 14. Since the enlarged head 40 is of greater diameter than the shank. 42 of the cam button 14, an annular, radially extending shoulder 54 is defined therebetween, to engage the right surface of the disc 20 incident to insertion of the cam button 14 into the disc opening 36.

As clearly shown in FIGS. 5 and 6, the shank 42 is Y longitudinally slotted, as indicated by reference numeral 56, to provide a long shank half 60 and a short shank half 58, both of the shank halves being semi-cylindrical in construction and having opposing, flattened surfaces 62 and 63 comprising the walls of the slot 56. As shown in FIG. 6, the right end of the slot 56 extends to and is generally coplanar with the shoulder 54 so that the shank halves 58 and 60 are spaced apart throughout their entire length, thereby permitting relative movement toward and away from one another. By the split shank construction. it has been observed that the shank halves 53 and inherently tend to diverge so as to provide a progressively larger effective diameter toward the free ends of the halves 58 and 60.

The cam button 14 is actually supported by the right ends of the shank halves 58 and 60 and this part of the button may conveniently be referred to as a supporting portion 44. In any event, the semi-cylindrical halves 58 and 60 coact to form a generally cylindrical shank that is of approximately the same diameter as the disc opening 36, but, in contrast to a solid shank, the slotted shank 42 is enabled to change its e'fi'ective diameter because of assaasa the somewhat resilient shank halves 58 and 60 which are capable of relative movement. In accordance with an aspect of the present invention, the shank 42 of the button 14 is so dimensioned that it is snugly accommodated by the.disc opening 36. Hence, during insertion of the button into the disc opening 36, it may be necessary to move the resilient shank halves 58 and 60 toward one another. With the shank halves 58 and 60 held together, the shank 42 easily slides into the disc opening 36. Of course, once the cam button 14 is inserted, the inherent resiliency of the shank halves 58 and 60 urges them apart, with the result that the cam button 14 is resiliently held in the disc opening 36. Furthermore, the inherent resiliency of the shank halves 58 and 60 offers a resistive force to the withdrawal, whether inadvertently or advertently, of the cam button 14 from the disc opening 36. Specifically, as the button 14 moves axially, the effective diameter of the shank 42 increases because of the generally diverging relation of the shank halves 58 and 69, thereby to apply a greater resistive force to the axial movement of the button 14. However, even though axial movement of the button 14 is rendered difficult by the diverging shank halves 58 and 60, the cam button 14 is nonetheless easily turned or rotated between its operative and inoperative position. This result obtains since the effective diameter of the shank 42 in the supporting portion of the button 14 is relatively fixed because the integral connection of the shank halves 58 and 60 with the head 40 and, in addition, the frictional resistive force developed by turning the button is less than the resistive force developed by axial movement of the button 14.

With the cam button 14 fully inserted in the disc opening 36, i.e., with the shoulder 54 abutting against the right surface of the disc 20 as viewed in FIG. 2, the left ends of both of the shank halves 58 and 60 extend to the left of the disc 20. The cam button 14 is so designed that only the shank half 60 coacts with the cam follower 16 and in this connection, the end of the shank half 58 is removed so that the shank half 58 has a length approximately one-half the length of the shank half 60. Accordingly, the left end of the shank half 60 extends to the left of the shank half 58 and comprises the camming part of the button 14. Thus, the camming part of the button 14 is spaced to the left of the disc 20 so as to coact with the cam follower 16 which is suitably supported from the plate 24. As shown in detail in FIGS. and 6, the left end of the shank half 60 is also of generally semicylindrical shape and includes a flat non-camming surface 64 that never engages the cam follower 16 and a generally curved camming surface 66 that engages and displaces the cam follower 16.

Considering now the cam follower 16 in greater detail, the cam follower 16 comprises a pair of resilient, electrically conductive arms 70 and 82, fixedly secured to and spaced apart at their left ends by a plurality of spacer blocks 72, the blocks 72 being suitably secured by fasteners 74 to an extension 76a of a generally U-shaped bracket 76. The free or right end of the arm 70 supports a follower stud 78 comprising a wedge-shaped block having an apex 78a for coacting with the camming part of the button 14 to move the resilient arm 70 upwardly and downwardly between the positions shown in FIGS. 5 and 6. The resilient arms 70 and 82, being made of electrically conductive material, are electrically connected at their left ends to the holding circuit for the main tuning shaft motor, while the arms 70 and 82 are electrically connected together by the control contacts 18 movable under the control of the follower stud 78. To this end, a contact 18a is suitably secured to the under surface of the arm 70 and a contact 18b is suitably secured to the upper surface of the arm 82 to be opposite the contact 18a. The contacts 18a and 18b are thus opened and closed under the control of the coacting follower stud 78 and the cam button 14.

Each cam button 14 is adjustably supported by the disc 20 and is movable between its operative and inoperative positions by an adjusting device 13 illustrated in FIG. 1. The adjusting device 13 comprises a hollow barrel 90, the left end of which engages a threaded aperture 92 provided in an arm 76!) of the U-shaped bracket 76 that is secured by fasteners 77 to the support 24. An axially movable adjusting rod 94 is concentrically located within the barrel and is resiliently urged to the right into a neutral position by a suitable coil spring located within a hollow part of the rod 94 and a flange 90a of the barrel 90. To prevent disassembly of the rod 94 and the barrel 90, a wire clip 96 is located in a groove defined in the left end of the rod 94, the clip 96 coacting with the left end of the barrel 90. The bracket 96 is so constructed that a metallic tip 98 fixedly secured to the extreme left end of the adjusting rod 94 is able to engage the adjusting slot 46 of the button head 40 when the adjusting rod 94 is manually moved to the left. To facilitate axial movement and rotation of the rod 94, a finger-gripping end 100, having a configuration best shown in FIG. 1, is provided. It will be appreciated that a screw driver, or the like tool, could be alternatively inserted in the adjusting slot 46 to turn the cam button 14.

Prior to use of the television receiver, the camming mechanism 10 is pre-set to stop the main tuning shaft 12 in the transmitting channel positions for the particular area in which the receiver is used. For example, in the Chicago area, the only transmitting channels are VHF channels, 2, 5, 7, 9 and 11 and, accordingly, the camrning mechanism 10 is preadjusted to cause the main tuning shaft 12 to successively stop in positions corresponding to the transmitting channels when the abovereferred-to control switch (not shown) is operated. Thus, since the twelve cam buttons 14 correspond to the twelve channel positions, those cam buttons 14 corresponding to the transmitting channels 2, 5, 7, 9 and 11 are set in their operative positions to coact with the cam follower 16 while those cam buttons 14 corresponding to channels 3, 4, 6, 8, 10, 12 and 13 are set in their inoperative positions out of engagement with the cam follower 16.

If it is assumed that all of the cam buttons 14 are in their inoperative positions out of engagement with the follower stud 78, then the stop 52 of each button abuts against its respective lug 38 to position its non-camming surface outwardly (or upwardly as seen in FIG. 5). In this position, each cam button 14 passes beneath and neither engages nor displaces the follower stud 78 as the disc 20 and main tuning shaft 12 are rotated. The cam buttons 14 corresponding to the transmitting channels are successively moved from their inoperative positions, illustrated in FIG. 5, to their operative positions, illustrated in FIG. 6, under the control of the adjusting device 13. Specifically, the disc 20 and shaft 12 are turned until the button 14 corresponding to the transmitting channel 2 is aligned adjacent to the adjusting device 13. The fingergripping end 100 is grasped and the adjusting rod 94 is pushed leftwardly, thereby compressing the coil spring, and is turned so that the metallic tip 98 mates with the adjusting slot 46 on the button head 40. Then, the adjusting rod 94 is turned so that the cam button 14 rotates in a counterclockwise direction, as viewed in FIG. 1, the shank halves 58 and 60 turning in the opening 36 and the shoulder 54 slidably moving on the right surface of the disc 20. This movement is permitted since the lug 38 does not coact with the head 40 but rather is disposed within the arcuate groove 48. During the counterclockwise movement, the stop 52 moves away from the lug 38 and the stop 50 moves toward the lug 38. This movement continues until the stop 50 abuts against the lug 38, at which time the scanning surface 66 faces outwardly (or faces upwardly as seen in FIG. 6), to coact with the cam follower 16. After the cam button 14 is moved in its operative position, as shown in FIG. 6, the gripping end 100 of rod 94 is released to permit the coil spring to return the adjusting rod 94 to its neutral position displaced rightwardly of the cam buttons 14. The balance of the buttons corresponding to the transmitting channels 5, 7, 9 and 11 are moved to their operative positions by the same procedure as described above. Thus, when each of the cam buttons 14 moves past the follower stud 73, the apex 78a of the stud 78 engages and rides onto camming surface 66, with the result that the follower stud 78 moves upwardly as viewed in FIGS. and 6. As a result of the upward movement of the follower stud 78, the resilient arm 70 and its associated contact 18a move upwardly, thereby opening the contacts 1811-4812 and breaking the holding circuit for the motor. Accordingly, the movement of the control shaft 12 is arrested.

It will be appreciated that a cam button 14 is moved from its operative position to its inoperative position by using the adjusting rod 94 to turn the button clockwise until the stop 52 abuts against the lug 38. Furthermore, in certain applications to obtain different results, the cam buttons 14 can be located in positions intermediate their operative and inoperative positions. From the foregoing description it will be appreciated that whenever a cam button 14 is adjusted by the adjusting device 13, or alternatively by a screw driver or the like, the cam button 14 is urged leftwardly so that the shoulder 54 more positively seats against the disc 20. Irrespective of the direction of force of the adjusting device 13, the coaction of the shoulder 54 with disc surface and the coaction of the shank halves 58 and 60 with the opening structure maint ains the cam button 14 generally perpendicular to the disc 20. Accordingly, the camming surface 66 remains in predetermined position relative to the disc 20 so that the follower stud 78 engages the camming surface 66 at the same angular position of the shaft 12 irrespective of the number of times the cam button 14 is adjusted. Consequently, the camming mechanism of the present invention overcomes the deficiencies of existing camnn'ng mechanisms in which the camming buttons are misaligned and the relative positions of the camming surfaces and cam followers are changed after one or several adjustments of the cam button 14, with the result that the operation of the cam mechanism is altered. Particularly, if the camming surface is moved as a result of the adjustment of the cam button, then the follower stud will either move upwardly prematurely or belatedly, thereby opening the contacts either too soon or too late. In the event of the former case, the motor is deenergized too soon and the spring-biased detent mechanism is unable to move the main tuning shaft into its channel position, with the result that the main tuning shaft 12 remains between the channel positions and the television tuner is not tuned to the desired station.

It will be appreciated that as the control shaft 12 rotates under the control of the electric motor, the cam buttons 14 likewise rotate and pass beneath the follower stud 78 of the cam follower 16. If a cam button is turned to its inoperative position as it passes under the follower stud 78, the follower stud does not engage the button 14 and the contacts 18 remain closed, with the result that the motor remains energized and the shaft 12 continues to move. However, if a cam button 14 is in its operative position as it passes under the follower stud 78, the stud 78 engages the button 14, the contacts 18 open, the motor is dcenergized, and the shaft 12 is stopped. More specifically, if it be assumed that the television receiver is tuned to channel 2, i.e., the cam button associated with channel 2 engages the follower stud 78 and, hence, the contacts 18 are opened to open the holding circuit for the motor, the receiver is then tuned to channel 5 by closing the control switch to close the energizing circuit for the motor. As suggested above, the energizing circuit and the holding circuit for the motor are in parallel so that the motor is energized even though the holding circuit remains opened under the control of the camming mechanism 10. Hence, with the control contacts closed, the motor is en ergized to turn the main tuning shaft 12 out of its channel 2 position and, thus, to turn the disc-hub arrangement 20, 21 and associated cam buttons '14. After the main tuning shaft 12 turns approximately six degrees, the contacts 18 close and the cam button corresponding to channel 2 moves out of engagement with the follower stud 78. The closure of the contacts 18 completes the holding circuit for the motor so that it is energized independently of the control switch and the shaft 12 is turned under the exclusive control of the camming mechanism 18.

During rotation of the man tuning shaft 12 from its channel 2 position to its channel 5 position, the cam buttons 14 associated with channels 3, 4, and 5, successively pass beneath the follower stud 78. Since the buttons 14 associated with channels 3 and 4 are in their inoperative positions with their non-camming surfaces ddfacing outwardly, the follower stud 78 does not engage and is not displaced upwardly by either of these cam buttons. However, since the button 14 associated with the transmitting channel 5 is in its operative position with its camming surface 66 facing outwardly, the follower stud 78 engages and rides up the semi-cylindrical camming surface, thereby to be displaced upwardly. When the shaft 12 is approximately six degrees from its channel 5 position, the contacts 18 open, thereby to open the holding circuit for the motor and effect its deenergization. Although the main tuning shaft 12 is no longer driven by the motor, the shaft 12 continues to move into its channel 5 position under the control of the spring-biased detent mechanism, which is operative within approximately seven and a half degrees of each channel position. Accordingly, the cam button continues to move with the result that the follower stud 78 rides onto the top of the camming surface, as shown in FIG. 6. The above-described operation is repeated whenever the receiver is tuned to another station. Furthermore, the above-described operation occurs irrespective of the direction of rotation of the main tuning shaft 12 and the cam buttons 14, because of the symmetrical construction of the semi-cylindrical camming surfaces of the buttons. However if a suitable bi-directional motor and associated control system is employed, the main tuning shaft 12 is arrested in either the adjacent higher or adjacent lower transmitting channel position in response to appropriate operation of the control system.

It should be appreciated that a camming button embodying the features of the present invention is extremely straightforward and clean in design and is quickly and easily mounted on a supporting disc without the use of additional restraining washers, screws, or other fastening devices. The cam button is susceptible to mass production and is readily produced, shipped, and handled. Furthermore, the buttons can be made out of a variety of long-life materials and, since the buttons are sup ported solely by the apertures of the supporting disc, any external wear caused by the use of additional assembly parts is entirely obviated.

Referring now to the FIG. 7 embodiment, another embodiment of the camming arrangement is illustrated and is identified generally by reference numeral 110. The camming mechanism is identical in construction to the camming mechanism 10 with the exception that a spur gear is employed instead of the disc 20. The spur gear 120 is suitably peened to a hub 121 which is fixedly secured to a control shaft 112 by a setscrew 128 located in a laterally extending opening 138. The spur gear 120 includes a plurality of spatially arranged openings 136, identical in construction and operation to the openings 36 described above, for accommodating a plurality of cam buttons 114 of identical construction to the above-described cam buttons, which buttons are moved between their operative and inoperative positions by an adjusting device 113, identical in construction to the device 13 described above. Similar to the FIG. 1 embodiment, the camming mechanism 110 includes a cam follower 116 embodying a follower stud 178 located at the end of an electrically conductive, resilient arm 170 which is suitably spaced from another electrically conductive arm 182 by a spacer block and fastener arrangement 172, 174 connected to a U-shaped bracket 176 similar to the bracket 76 described above. The follower stud 178 coacts with the cam buttons 114 to open a pair of contacts 118a, 118b respectively secured to arms 170 and 182.

It should be appreciated that because of the unique construction and operation of the camming mechanism 110, the cam buttons 114 can be mounted on a spur gear 120 which comprises a part of a gear train 122 interconnecting an electric motor with a main tuning shaft 112. The gear train 122, for example, comprises the spur gear 120, an idler gear 123, and a pinion driving gear 125 mounted on the output shaft 127 of the motor. Hence, assuming that the shaft 112 comprises the main tuning shaft of a television receiver, the output gear of the gear train 122 can be modified to include the plurality of openings 136 for receiving the cam buttons 114. Accordingly, a disc 20, hub 21, and setscrew 30 can be entirely eliminated in the manufacture of a television re ceiver with the attendant cost savings to the manufacturer. The operation and performance of the camming mechanism 110 and its cam buttons 114, cam follower 116, adjusting device 113 is identical to the above-described FIG. 1 embodiment, and in the interest of avoiding unnecessary duplication of description, the structural and operational details of the FIG. 7 embodiment are not repeated.

While several embodiments described herein are at present considered to be preferred, it is understood that various modifications and improvements may be made therein, and it is intended to cover in the appended claims all such modifications and improvements as fall Within the true spirit and scope of the invention;

What is desired to be claimed and secured by Letters Patent of the United States is:

1. In a cam arrangement, a cam button comprising a generally elongated cylindrical body including an enlarged head portion having means for accommodating an adjustment device and defining a shoulder adapted to coact with a support, a camming portion at an end of the 10 body, and a support engaging portion intermediate said head and engaging portions and adapted to be inserted in an aperture in the support, said support engaging portion and said shoulder adapted to coact with said support to maintain said camming portion in predetermined relation to said engaging portion irrespective of adjustment of said head by the adjustment device.

2. The arrangement of claim 1 wherein said body is slotted to provide a pair of shank halves of unequal lengths thereby said camming portion adapted to be inserted in said aperture to resiliently hold said cam button in place.

3. The arrangement of claim 2 wherein one of said shank halves is partially removed so that the other shank half solely comprises the camming portion, said camming portion including an arcuate camming surface and a flat non-camming surface, said flat surface comprising a continuation of one of the walls of the slotted body.

4. In a cam arrangement, a support having an aperture therein, a cam button having an elongated cylindrical body portion and an enlarged head portion, said head portion having means for accommodating an adjustment device and defining a shoulder adapted to coact with said support, said body portion receivable in said aperture and having a slot substantially extending over the length of said body portion and defining a pair of shank halves, one of said shank halves being shorter than the other to define a camming portion at the end of said body portion, said shoulder having abutment portions engageable with said support to limit rotative movement of said cam button relative to said support, said shank halves resiliently restraining axial movement of said cam button relative to said support.

References Cited in the file of this patent UNITED STATES PATENTS 908,790 Mallam Ian. 5, 1909 1,468,275 Briggs Sept. 18, 1923 2,066,246 Bolton Dec. 29, 1936 2,255,012 Lake et a1 Sept. 2, 1941 2,621,266 Gretener Dec. 9, 1952 2,832,408 Manning Apr. 29, 1958 2,863,409 Schumann et al. Dec. 9, 1958 2,887,901 Immel May 26, 1959 

